1. Field of the Invention
The invention relates to an actuating means able to be activated by fluid power comprising a flexible contractible tube extending between two spaced apart head pieces, which on being acted upon by fluid in its interior space undergoes radial expansion and thereby simultaneously transmits axial forces, due to contraction, to the head pieces, the flexible contractible tube comprising an elastically deforming flexible tube body, which has supporting means for contributing to increasing it strength and/or to force transmission.
2. Description of the Prior Art
Actuating means of this type may for instance perform the function of drives, in which case they are able to be employed as an alternative to conventional fluid power cylinders. In the case of a design indicated in the European patent publication 0 161 750 B1 two head pieces are connected by a flexible contractible tube, which comprises an elastomeric flexible tube body and furthermore a fabric-like strand structure, which coaxially surrounds the flexible tube body. The strand structure provides a supporting means, which increase the strength of the flexible contractible tube while simultaneously optimizing the transmission of the contraction forces to the head pieces. If the inner space of the flexible contractible tube is subjected to fluid under pressure, there will be a radial expansion, and the head pieces are moved toward one another, such movement being able to be employed for the actuation of any desired components and/or means.
Without the supporting means contributing to increasing strength and/or to the transmission of force, in the case of a flexible tube body of elastomerically deforming material there would be the problem that same would radially expand under the action of pressure, and would not cause an sufficient transmission of tension forces to the head pieces and furthermore in the case of an excessive action of pressure the there would be the danger of bursting. On the other hand there are limits as regards the design of the strand structure serving as a support, if the actuating means is below a certain overall size. In the case of a embedding strand structure in the flexible tube body's material, as is indicated for example in the German patent publication 29,908,008 (utility model), there is no possibility of dealing with such problems.